Control apparatus



' Feb,A 7,y 1939.

H. G. FISCHER CQN'I'ROL APPARATUS Filed April 16, 1956 2 Sheets-Sheet l v Feb. 7, 1 939. Y H. @FISCHER 'l 2,145,358

l I CONTROL APPARATUS Filed April 16, 1936 2 Sheets-Sheet 2 I YPatented Feb. 7, 1939 i l t UNITED STATES PATENT OFFICE ooN'rRoL APPARATUS Herman G. Fischer, River Forest, 111;, assignor to H. G. Fischer & Co. Inc., Chicago, Ill., a corporation of Illinois Application April 16, 1936, Serial No. 74,665

13A Claims. (Cl. Z50-95) The invention relates generally toautomati- Fig. 2 is a vertical sectional view taken through y callytimed apparatus, and more particularly to the-bucky diaphragm substantially along the line such apparatus wherein the operating period 2-2 of Fig. 3. which is tobe accurately timed takes place dur- Fig. 2a is a fragmental perspective View of the '5 ing the cycle of movement of a shiftable element timer showing the indicating means for the se- 5 f ,which constitutes one of the operative parts of lecting switch. vthe apparatus. Fig. 3 is a fragmental plan view of the bucky j' illustrative example of such apparatus is diaphragm. y kfound in an X-ray machinewherein the ray Fig. 4 is a wiring diagram of the apparatus with 10 source is energized for a predetermined time incertain of the control elements shown diagraml0 v `terval during which a shiftable filter, known commatically in association therewith.

- mercially as a bucky diaphram, moves trans- While I have shown in the drawings and will kversely and preferably at a constant rate between herein describe -in detail the preferred embodithe ray source and the photographic plate so as ment of my invention, it is to be understood that i5 to insure clarity and sharpness in the resulting I do not rthereby intend to limit the invention to l5 lexposure of the plate. the specic form disclosed, but aim to cover all An important object of the present invention is modifications and alternative constructions fallto provide an apparatus of this general character ing Within thc Splrt and Sccpc 0f the invention embodying, in combination, a timing mechanism as expressed in the appended claims.

v whereiny the accurately timed operating period of In. the form chosen for disclosure herein, the 20 the apparatus as determinedby the timing mechinvention is embodied in an X-ray machine I0 anism is positively and'accurately interrelated to having atable l l upon Which the patient iS placedand controlled bythe operativemovement of such A light 01 X-Iay SOl-lcc l2 iS mcllntcd fOr adshiftable element ofv the apparatus. justment vertically on a column I3 which is carf More particularly it is an object of the invenl ried on -a control cabinet I4. Beneath the table 25 'tion to provide Xnrary apparatus wherein the op.; Il S mounted a, photographic plate holder l5,

f erative period of exposureof the plate is deterthisl hcdcl' being adjustably Secured t0l thc table rnnedby timing apparatus of unusual accuracy and preferably having a bucky diaphragm Vwhich is interrelated to and controlled by a shift- V(Fig. 3) aSSOciate theTcWth- On the tcp O'f r able bucky diaphragm so that the entire exposure thc contlcl cabinet f4 S PJv c0nt1'01 Panel I7, and 30 f period takes place while the bucky diaphragm is detachably hung on l the cabinet is a portable moving at a. uniform speed, motor driven timer I8 of the type disclosed and Another object is. to provide an apparatus of claimed in the copending application of Howard this character wherein, under certain predeter- H. Osborn, Serial N0. 43,379, lcd Octcbcl 3, 1935- mined arrangements of the apparatus, an ac- In accordance with the present invention the 35 V.curate timing mechanism is so related to the timer I8 embodies multiple switch mechanism I9 bucky diaphragm as to insure proper operative (Fig. 4) and a control knob 20, and is associated movement of the bucky diaphragm during thek with the bucky diaphragm I6 and with the eleckemi-,111115 operatilfigv period olf the apparatus c011- trcal circuit Of the X-Iay Source l2 in Such a,

lio trolled by such mechanism. manner that the testing and operation of the 40 ,f .Another object is to .provide apparatus @f1-,his machine and its control apparatus are materially ycharacter having an accurate timing mechanism simplified. Such association is shown in the cirand a bucky diaphragm, adapted in one se1ective cuit diagram. which is illustrated in Fig. 4 of the ysetting of the apparatus to act as an interrelated drawings and Wi11 nOW bc described- 475 control for the exposure period,` in another se- Since the circuit for Supplying energy to the 45 plected settingto control the rexposure period solely X-Iay SOUICB l2 iS generally 01d and Well known bymeans of the timingmechanism, `and in a, it will be unnecessary to describe itin detail. An third,selected setting to control the apparatus autotransformer 2I has its primary terminals in "avmanner suited for test purposes. connected to suitable alternating current supply .Y lf.r Other objects and advantages will'become apvlines LI and L2, and thc Scccndaly is provided 50 parent from the following description, taken in with adjustable taps or voltage controls 26A, 26B Vconnection with the accompanying drawings, in and 28C. One secondary terminal 2Ivis arranged which: l ,to be connected to one side of the primary of a Fig. lisa perspective View of an X-ray machine power transformer 22 through a circuit breaker embodying the features of the invention. `32, awire 33, a contactor 24 and a wire 33', where- 55 as the other secondary terminal 2 I is connected to the other side of the primary of transformer 22 by means of a wire 25', the main filament control 25C and a wire 25. A filament transformer 23 has one side oi its primary connected to the end tap of the winding of transformer 2l by a wire 23', and has its other side connected through an auxiliary filament control 23A and a wire 23 to the control 25C.

'IhecontactorZisnormally open and, when the ray source i2 is to be energized, low voltage control current is supplied from a secondary transformer winding 2l to the actuating coil 28 .of the contactor through cl-osure of a control relay switch 33. Thus a lead wire L3 connects one side of the secondary 2l to one terminal of an actuating coil 3l of the relay 30, while a lead wire L4 from the other side of the secondary 21, in series with circuit breaker 32, wires 33, 34 and 35 and parallel branch leads 35, is connected to corresponding terminals 3S of a pair of three-terminal outlet sockets 39. A wire 4G and parallel branch leads 5I connect the other terminal of relay coil 3i to corresponding terminals 42 of the sockets 39. One terminal of actuating coil 28 is connected by lead 52 to lead L3, while the other terminal is connected by lead 52, the relay 3i! and lead 35 to wire 35 and thence through wire 54 to the other side of the secondary winding 2l. Thus it will be evident that the relay V35i, and hence the contacter 24 and the source I2, will be venergized. upon closure of a circuit across the terminals 38 and 42.

For use in preliminary testing of the light or ray source I2, a normally open foot switch 43 is preferably provided for closing the circuit across terminals 38 and 42. This switch, which may be closed by depressing a button 43', is connected across said terminals by the use of two contacts 44 and 45 of a three-contact attachment plug 45, which plug is inserted in one of the sockets 33. Wires 13'! and 48 connect contacts 44 and 45 to the two sides of the foot switch 43.

For simplicity in use the third terminals 5I! of the two sockets 39 are interconnected by a wire 5I, and a wire 52 from one of the terminals 5G connects the same with lead wire L3 and with one end of the contacter coil 28. Thus a. source of line voltage is provided between terminals 38 and 50 independently of the relay 30, andthis Vsource of line voltage is employed in operating and controlling the timer IB and the other elements of the control apparatus, as hereinafter morey fully described.

In addition to testing of the ray source I2 by means of the foot switch 43, the invention in its preferred form makes provision for timing the operation of the ray source both with and without operation of the bucky diaphragm. Thus when the control knob 2li of switch I9 is in the center position shown in Figs. 2a and 4, a pointer 'I5 extending radially from the knob: points towards the timer position and the timer I 8 is connected into the control circuit of the machine. When the knob 25 is rotated counterclockwise (Fig. 2a) so that the pointer extends in the direction of the bucky timer position, the timer I8 is connected to operate in conjunction with the bucky diaphragm. When the knob 25 is rotated clockwise to the test position, a manually operable test switch 9i] (Fig. 4) is effective to control the ray source I2.

The fbucky diaphragm I6, as illustrated most clearly in Figs. 2 and 3, is slidable on rods 56 formovement transversely of the table II and across the path yof the X-rays from the source I2 to a photographic plate which is placed on the plate holder I5 below the bucky diaphragm. Prior to starting the machine the operator pulls the bucky diaphragm to the right hand end of its travel (Figs. 2 and 3) and during the operation of the machine the bucky diaphragm moves at a preselected speed towards the left, to the yother end of its travel.

In one setting of the selecting or control switch I9, the present invention provides for the interrelation of the timed operating period of the machine Ywith the shifting movement of the bucky diaphragm i5, and to this end the bucky diaphragm, in its shifting movement along guide rods 5 5 of frame 55, is arranged to govern the closure of a switch 55 (Figs. 2, 3 and 4) carried by the frame 56. As shown in Fig. 4, the switch 55 is actuated by a pair of lugs or pins 5'I and 5'I projecting from one edge of the bucky diaphragm I5 in a Vdirection transversely of the path of movement of the bucky diaphragm. The bucky diaphram, as herein shown, is urged to the left by a spring 58 from the full line position of Figs. Z and 3 to the dotted line position of Fig. 4, and during such movement its speed is governed by a dashpot 59. The cylinder 59' of the dashpot is Xed on the frame 55 while-a movable piston rod 59 extends therefrom and is xed to a slide member 55" on one of the guide rods 55. A link I 6 connects the slide member 56" to the bucky diaphragm I 6 so that the bucky diaphragm and the piston rod 59 move together. By extending the piston rod 59" .beyond the front of the frame 55, a loading rod 6I) is provided whereby the bucky diaphragm may be drawn manually to the right to its full line position of Fig. 2. In this right hand position the bucky diaphragm is releasably held by a spring biased latch 6I pivoted on the frame 56 by a pin 6I and engageable with a hook-shaped member 5I carried by the frame of the bucky diaphragm I5. To initiate its operative return movement, the bucky diaphragm I5 may be released by a release cord 52 which is connected t0 an arm S2 of the latch 5I and extends outwardly through the front of the frame 56. As another release means for the latch 5I, a solenoid 63 is mounted on the frame 55, and its core 55 is operatiVely connected to the arm 62 of the latch by a pin 64 which projects horizontally from said armature and extends loosely through a transverse hole in the arm 62. Springs I6I and |62 serve to move the latch 5I to its hook-engaging position.

Upon release of the latch 5I the bucky diaphragm VIt starts toward the left under the influence of spring 58 until it reaches the maXimum speed determined by the dashpot 59. A valve rod 65 mounted Within the loading rod 60 may be employed to vary the by-pass opening of the dashpot and thereby vary the predetermined maximum speed of movement of the bucky.

As best shown in Fig. 4, the switch 55 comprises a pair of normally engaged spring contacts 55 and 55". When the bucky diaphragm is in its left hand position of Fig. 4 the lug 5'I engages contact 55 to swing it to the open position shown and this open position is maintained by a spring latch 65 as the bucky diaphragm is shifted back again to the right. During the terminal portion of such right-hand or loading movement, the lug 5l engages a hook 5l on the contact 55" to move this contactl to an openv position (Fig. 2)

y beyond the range of contactl 55' which is then f released due to actuation of the latch 68 by lug K 51'., The switch 55 is then conditioned for closure as the bucky diaphragmand its lug 51 return to :the left, and such closure takes place only after the bucky diaphragm has reached its constant speed as determined by the dashpot 59.

' Under some circumstances the dashpot control ofthe bucky diaphragm may be used for timing the operation of the machine, but for the purpose yof [extremely accurate timing not subject to change due to viscosity changes of the fluid in the .f Adashpot, the invention combines with the bucky rmentioned Osborn application.

diaphragmV an electrically operated timer of the type disclosed and claimed in the hereinbefore The action of the bucky diaphragm switch 55 Ain producing a coordinated control of the bucky diaphragm and the timer I8 in governing the exposure period is obtained through selective setting' of the multiple switch I9 of the timer by its o kcontrol knob 28. To this end the 'multiple switch 9, as illustrated hereinin Fig.l 4 comprises eleven switch contacts a, b, c, d, e, f, g, h, i, j, and Ic,r keach mounted `on an individual iiexible arm 18,

. all of which arms are carried on anY insulating bar f 1| and are controlled as toposition or engagement by a cam 12 carried by the shaft 28 of knob 28. The switch I9 and its actuating cam 12 are housed within the casing of the timer I8 and a shaft 28 connecting the cam with the knob 20 is journaled inandprojects through the top wall I8 of the timer as shown in Fig. 2a so as to support the knob 28 voutside of and adjacent to the wall i8.

On the outer face of the wall I8 there are indicatedthree positions of the switch, namely a bucky timer position, a timer position, and a vfte'st position. As mentioned hereinbefore, a pointer 15 on the knob 28 cooperates with these yindicia to show the setting of the switch I9.

f. :In Figs. 2a and 4 the parts are shown in the When the switch is in the setting shown in Figs. 2 and 4, projections VV13 and 14 of the arms which carry contacts d and g respectively are adjacent to opposite sides s ofthe cam 12.

When the knob 28 is turned to the right (Fig. 2a) to indicate test position, a large lobe 12 of f the camf12 presses the arm 13 upwardly so as to connect contacts d, cand b and, in the same movement, a pressure link 16, between arm 13 and anextension of the arm 18 of contact a, shifts contact arto an open position with relation to f 'When the knob 28 is turned to theleft (Fig. 2a)

V rto indicate the bucky timer position, contacts y'a and b remain closed while the connection of contacts d and e is opened by the action of lobe 12. Opening of contacts d and e while contacts a and bfremain closed is permitted by lost motion kconnection 16 between the link 16 and the arm s' of contact a. In such rotation of the cam, lobe l engage contact k. f

12Vl shifts the arm 14 to separate contacts j and g,

. while links 11 and 18, between arm 14 and extensions of the arms'of contactsV h and 7', cause contact It Vto engage contact i, rand contact y' to -y k ASgdescribed in detail in the aforesaid Osborn 3 application, the timer I8 embodies a synchronous drive motor 88 (Fig. 4) acting through reduction gearing 88 to rotate a shaft 88" in a counterclockwise direction. A pair of collector rings 8| and 82 are mounted for rotative movement with the dial of the timer in a counterclockwise direction; the rings 8| and 82 being in insulated, nonrotative relation to each other. Connected in series with the rings is a switch 83 having a fixed contact 83a carried on the ring 8| and a pivoted contact 83h on the ring 82 and normally urged to switch closed position by a spring 83C. To open the switch 83, a switch actuating member or pin 83 is mounted for rotation with the shaft on an arm 88a fast on the shaft, and in such rotation the pin 83' is arranged to engage a lug 83 to open the switch 83. To set the timer for a denite period, the collector rings and their switch 83 are advanced or rotated the desired amount in a counterclockwise direction with relation to the shaft 88" and the pin 83 so as to separate the lug 83" from the pin 83', and upon starting of the motor 88 thepin 83 is advanced until it opens the switch 83. To permit such advancing of the collector rings 8| and 82, spring contacts 8|' and 82 are provided in engagement respectively with the edges of rings 8| and 82 as terminals therefor, and a ratchet means (not shown) may be employed to hold the rings 8| and 82 in their set position.

In the bucky-timer position of control knob 28, the normally open hand switch 98 is closed by the operator to release the bucky diaphragm I6 through the establishment of a circuit across terminals 58-38 and through the solenoid 63. This circuit includes wires 8| and 92 connecting terminal 58 with contact lc; contact 7' and wires 93 and 94 connecting contact i to the hand switch Y 98; the hand switch 98 and wires 95 and 98 connecting the hand switch 98 to contact h; contact i and wire 91 connecting contact i with one side of solenoid 63; and wires 98', 98 and 99 connecting the other side of solenoid 63 with the terminal 38. This circuit energizes solenoid 63 so as to actuate the latch 6| and release the bucky diaphragm i6 for movement to the left by its spring 58.

After the bucky diaphragm has attained the speed determined by dashpot 59, the movement of lug 51 (Figs. 2 and 3) releases hook 61 and Vthereby permits closure of the bucky diaphragmswitch 55 so as to establish a first circuit through the collector rings 8| and 82 and the timer motor 88 and start the timer I 8, and simultaneously to establish a second circuit through the collector rings 8| and 82 and the control relay 38 so as to energize the light or ray source |2.

TheY rst circuit thus established to the timer in the bucky-timerfsetting is across terminals 38-58, and includes wires 99, 98, switch 55, wires |08 and |8| connecting switch 55 to one side of switch 83 through collector ring 8|, wires |82 and |83 connecting the other side of switch 83 to one terminal of the motor 88, through the motor, through wire |84 to wire 9| and thence to terminal 58.

'I'he second circuit, which is established simultaneously to the light control relay 38 when the bucky diaphragm switch 55 is thus closed, is across terminals 38-42, and due to the fact that the coil of the relay 38 is in circuit between terminal 42 and L3 ythe establishment of this circuit causes the source I2 to be energized. The circuit across terminals 38-42 includes terminal 38, Wires 99, 98, switch 55, wires |88 and |0I, 75

collector ring switch 83, wire |32, wire M35 which connects wire HB2 to contact a, the Contact b,

and wire E06 which connects contact b with terminal 42.

Since the collector ring switch 83 is included in .the circuit which controls source i2 as well as the circuit which supplies current to the timer motor 8i), it will 4be apparent that, when the pre- .set period oi operation oi the timer iii has elapsed, the consequent opening of the switch 83 will cause the source I2 to be deenergized and the operation of the timer motor Si) to be stopped.

In the use of the apparatus in the bucky timer setting, the valve of the dashpot 59 is set so that the period of constant-speed movement of the bucky diaphragm is greater than the period lset on the timer i8, and hence the bucky diaphragm continues movement after the light source has been shut on. In this continued movement the lug 5'! engages contact 55 and opens the switch 55 so as to prevent use of the apparatus until the bucky diaphragm hasv been reloaded or moved to its right-hand position. Even then, the timer must be reset to a position away from its stopped position, and the hand switch S or the Vrelease cord must be actuated in order to initiate another cycle of operation.

When the exposure is-to be made without the bucky diaphragm and simply under the control of the timer i8, the control knob 2Q is shifted to the timer position with the resulting change of the relation of the contacts of the multiple switch i9 as hereinbefore described.

In this setting of the control knob E3, the operation oi the X-ray is primarily under the control of hand switch in that this switch is in circuit with both the timer motor Sii and the circuit to the control relay 3E). The hand switch 'Sil must therefore be held in depressed or closed position during the entire operating period, and opening oi this switch at any time during the desired period will cause the timer to stop :and the source l2 to be deenergized. In a secondary sense, the operation of the apparatus in this setting of knob 2i) is under the control of the timer I8, since the timer must initially be set, and after being set operates to limit and terminate the operating period despite continued closure of the hand switch QB.

The necessary circuit across terminals i2-33 to energize the X-ray source i2 is provided from terminal d2 by wire ii, contacts b, a, wires m5 and |02, collector rings 82 and Si and switch 83 of the timer, wire lili, contacts d, e, wire s, hand switch 9B, wire 95, contacts f, g, a wire liti connesting contact g to the junction of wires 9S and Q9, and wire 99 to terminal 3B.

The circuit across terminals 38-5!) is provided from terminal 38 through wires 99 and l iii, contacts y and wire $5, hand switch 9S, wire 9S, contacts e and d, wire lEi, collector rings 8i and 82 and their switch S3, wires EQ2 and ID3, the motor Sil, and wires li and 9i to terminal 5i?.

In the test setting of control lrnob 2t, the hand switch Sii constitutes the primary control .o both the timer and ray source operation in a manner comparable to the control exercised in the timer setting, with the distinction,l however, that the period of operation of the ray source is not and cannot be limited and terminated by the timer E8. Hence the timer i8 may in this setup be used merely as an indicator at the option of the user; but in the event that the timer is notset by the user, the ray source tacts c and d, wire il, collector rings 8| and'Z and their switch 53, wires m2 and E63, the motor 8S, and wires` iiifi and 9i to terminal 50.

The circuit for energizing the X-rayv controlrelay 3@ is across terminals 38 and 42, and in this setting of the control knob 2E is provided from terminal Sii, through wires 9S and H0, contacts g and f, wire 95, hand switch 90, wires 94 and lil, contacts c and b, and wire IDS to terminal 52.

ciaim as my invention: Y

i. The combination, `for use with an X-ray machine utiiizing yphotographic plates, of shiftable means movable across the plate during ythe operation of the machine, a precision timer for the E'l-ray machine having a synchronous motor driving the same and a normally closed switch, means including a circuit through saidy switch operable by said switch to control both said motor and the X-ray'machine, said circuit including a pair of normally -open contacts, and control means on said rst mentioned shiftable means operabie to close said contacts after said rst mentioned means has attained a uniform speed movement imparted to said screen by said spring,

lockins means for holding said screen at one eX- tremeof its movement against the action of said spring, a solenoid operable when energized to reto the action oi said spring, a circuit including said solenoid and a normally open switch handV operated to complete the circuit, a timer for the X-ray machine having` a synchronous motor driving the sam-e and a normally closed switch,

said switch operating to control both said motor and said X-ray machine, a circuit including said last mentioned switch, said motor and a pair of normally open contacts, and means controlled by said screen closing said contacts after the screen has attained a uniform speed to complete said last mentioned circuit and initiate operation of said timer and said X-ray machine, said means maintaining4 said' contacts closed for a period exceeding the period oi operation of said timer@ 3. Control apparatus adapted for association with the `Roentgen ray source of an X-ray machine, said apparatus comprising `a movable screen, a precision timer driven by a synchronous motor and having a Vstop switch closed during the timed period and opened at the en-d of said period, means for moving'said screen, means for initiatingoperative movement of said screen independently of said timer, electrical connections including a switch operable under the-controlof and duringithefoperative movementfof said screen vlease -lccking means and-free said screen l Y so , 'whereby to place said hand switch in control of trol means being operable in another setting to Vtoenergize said timer motor and rsaid. ray source,

said timer motor and said ray source being inrcluded insaid connections so as to be under the control of said stop switch of said timer.

4. In an X-ray machine having a source of X-rays, a motor driven timer having a timing switch, 'and a movable bucky diaphragm, the

- combination of control means having a plurality ofrsettings, electrically operated means for initiating movement of said bucky diaphragm, a control switch operated by said bucky diaphragm in its movement, and a hand switch, said'control means having electrical conductors associated ktherewith and operatively connected inea first ysetting of said control means to connect said hand switchin circuit with said electrically operated means for initiating movement of said bucky diaphragm, to connect said conductors to y provide a circuit through said control switch to place said bucky diaphragm in operative control of said timer and said source for starting opera- Ation of the timer and said source,'and to confnect said con-ductors to form an energizing circuit for said ray source including said timing 'switch whereby to place said timer in control of said source to terminate operation of said source, said control means being operable in a second setting to connect said conductors to form an energizing circuit for said ray source including said hand switch, said motor, and said timing switch,

' the Vstarting and stopping of said timer and said source and to place said timer in a dominating control of said source to stop the same regardless ofr the closure of said hand switch, and said convconnect said conductors to form an energizing -c'lrcuit for saidr ray source including said hand switch and said motor whereby to place said hand switch in control of the starting and stopping of said timer and in control of the starting and Ystopping of said source independently of the adapted to be moved during said interval, means for kmoving the bucky diaphragm at a uniform rate, and means operatively interconnecting the timer, the source of X-rays, and the bucky diaphragm operable to effect an interrelated control of the period of operation of said source vof X- rays by said timer and the bucky diaphragm movement. 6. In an X-ray machine having a source of X-rays, a bucky diaphragm,fme ans for moving i the bucky diaphragm at a uniform rate, a synchronous motor-driven'precision timer operable to stop the machine after apreselected time interval, a control circuit for said X-ray source including said timer, and means actuated byV said bucky diaphragm and associated with said control circuit operable to initiate the operation of said timer and said source of X-rays.

7.7I'nanX-ray machine having a source of i X-rays, atiming mechanism therefor including a device o-perable after a predetermined time to .70

` source, a commoncontrol means for starting the f stop'said mechanism and to deenergize said ray Vifroperation of said mechanism and for energizing ysaid source,` and a control circuit for deenergizlng said source operatively associatedwith the device of said timing mechanism` to deenergize said source after a preselected time interval, a shiftable screen movable through an operating stroke from a rest position to a predetermined speed and thereafter in the balance of said stroke at the predetermined speed, and means governed by said shiftable screen to actuate said common control means to energize said source and start said timing mechanism after said screen has attained said predetermined speed.

8. In a ray producing apparatus, a source of rays, a shiftable element, power means operable to shift said element, governing means for maintaining a uniform rate of movement of said shiftable element after it has attained the predetermined rate, a control circuit including an adjustable precision timer operable to terminate the operating period of said ray source, means in said control circuit actuated by said shiftable element after it has attained the predetermined rate of movement to initiate operation of said timer and said ray source, and means for moving said shiftable element.

9. An apparatus comprising, in combination, a first operating element, a shiftable element, means including a spring and a hydraulic governing means for driving said shiftable element from a rest position up to a predetermined speed and thereafter continuing the movement of said element at said predetermined speed through an operating stroke of said shiftable element, a control circuit for said first operating element including an adjustable timer operable to terminate the operating period of said iirst operating element, a switch in said control circuit closed by said shiftable element after it has attained said predetermined speed to initiate operation of said timer and said first operating element, and means for releasing said spring to initiate operative movement of said shiftable element.

l0. In an X-ray machine having an X-ray tube and photographic plates adapted to be exposed to the X-rays from the tube, a bucky diaphragm shiftable across the plate intermediate the plate and the X-ray tube, means for shifting the bucky diaphragm including a spring cocked by manual movement of the diaphragm in one direction and hydraulic fluid governing means for maintaining a predetermined rate of movement after the bucky diaphragm has been brought up to that predetermined rate, a control circuit for the X-ray tube including an adjustable timer operable to terminate the operating period of the X-ray tube after a predetermined interval, a switch in said control circuit operable by said bucky diaphragm after it has attained the predetermined rate to close the control circuit and initiate operation of said timer and the X-ray tube, and means for releasing said bucky diaphragm to the action of said cocked spring.v

11. The combination, for use with an X-ray machine, of a synchronous motor driven precison timer, means operatively connecting said timer to control the termination of the period of operation of the X-ray machine, a reciprocably mounted bucky diaphragm, means for moving said bucky diaphragm in one direction during an exposure, and means operated by said bucky diaphragm during the movement thereof controlling the initiation of operation of said timer. 12. The combination, for use with an X-ray machine, of a synchronous motor driven timer controlling the termination of the period of contacts, said contacts when closed functioning to start the machine and said timer simultaneously, a movable bucky diaphragm, means ior moving the bucky diaphragm, and means operable by the bucky diaphragm after a predetermined movement thereof to close said contacts and maintain the same closed longer than the period for which the timer is set.

13. In an X-ray machine, the combination of a timer operable to control the periodl of operation of the X-ray machine, a. control switch having a plurality of settings, a movable bucky diaphragm, electrical connections effective in one setting of said control switch to form a circuit including said timer and a switch operable by the bucky diaphragm in its' movement to energize and initiate operation of said timer, a1 hand switch, electrical means including'a sec-V ond circuit connected in said one setting of said control switch to include said hand switch and in another setting of said control switch to include said timer and said hand switch and renider said hand switch effective through said.: third circuit to govern directly the starting and stop'- ping oi. said time-r.

HERMAN G. FISCHER', 

